The overall purpose is to develop an in vitro assay of tumor cell invasion of tissue matrix barriers. Purified collagens, including basement membrane collagen and other matrix proteins, will be impregnated in soft agar as a means of simulating tissue matrix. Tumor cell penetration of these artificial barriers will be quantitated at various times in culture. The role of hormones and proteases in the invasion will be studied using a wide variety of tumor cells with known metastatic capacity.